Having had the bill split? (2,1,6)
I believe the answer is:
do a runner
If this is the answer I cannot explain how the clue works.
(Other definitions for do a runner that I've seen before include "Zambezi cataract" , "Nun adorer may escape on the trot" , "Embroider a table cloth" , "Avoid paying" , "Scarper (informal)" .)